<?php
declare(strict_types=1);

header('Content-Type: application/json; charset=utf-8');

require_once __DIR__ . '/../app/channel_data.php';

function respond(int $status, array $payload): void
{
    http_response_code($status);
    echo json_encode($payload, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES);
    exit;
}

channel_app_bootstrap();
$method = $_SERVER['REQUEST_METHOD'] ?? 'GET';
$userId = channel_current_user_id();

try {
    if ($method === 'GET') {
        if (isset($_GET['stats'])) {
            respond(200, ['success' => true, 'data' => channel_stats()]);
        }

        if (isset($_GET['history_for'])) {
            respond(200, ['success' => true, 'data' => channel_history((int) $_GET['history_for'])]);
        }

        if (isset($_GET['id'])) {
            $channel = channel_get((int) $_GET['id']);
            if (!$channel) {
                respond(404, ['success' => false, 'error' => 'Channel not found.']);
            }
            respond(200, ['success' => true, 'data' => $channel, 'meta' => [
                'editable_fields' => CHANNEL_EDITABLE_FIELDS,
                'locked_fields' => CHANNEL_LOCKED_FIELDS,
                'options' => channel_distinct_options(CHANNEL_FILTER_OPTION_FIELDS),
            ]]);
        }

        respond(200, ['success' => true, 'data' => channel_list($_GET)]);
    }

    $rawBody = file_get_contents('php://input');
    $payload = $rawBody ? json_decode($rawBody, true) : [];
    if (!is_array($payload)) {
        $payload = [];
    }

    if ($method === 'PATCH') {
        if (isset($_GET['bulk'])) {
            $result = channel_bulk_patch($payload['ids'] ?? [], $payload['fields'] ?? [], $userId);
            respond(200, ['success' => true, 'message' => 'Bulk update applied.', 'data' => $result]);
        }

        if (!isset($_GET['id'])) {
            respond(400, ['success' => false, 'error' => 'Missing channel id.']);
        }

        $result = channel_patch((int) $_GET['id'], $payload['fields'] ?? $payload, $userId);
        respond(200, ['success' => true, 'message' => 'Channel updated.', 'data' => $result]);
    }

    respond(405, ['success' => false, 'error' => 'Method not allowed.']);
} catch (RuntimeException $e) {
    if (str_starts_with($e->getMessage(), 'FORBIDDEN_FIELD:')) {
        respond(403, ['success' => false, 'error' => 'Attempted to modify a locked system field.']);
    }
    respond(500, ['success' => false, 'error' => $e->getMessage() ?: 'Unexpected runtime error.']);
} catch (InvalidArgumentException $e) {
    respond(422, ['success' => false, 'error' => $e->getMessage()]);
} catch (Throwable $e) {
    respond(500, ['success' => false, 'error' => 'Unexpected server error.']);
}